New techniques developed during this year include an astrocytoma tumor model, two ways of performing double label quantitative autoradiography, two approaches for analyzing blood-tissue transfer, and an awake animal ventriculocisternal perfusion procedure. Blood-tissue distribution studies of antitumor agents indicated that spirohydantoin mustard rapidly crosses the blood-brain barrier (BBB) and enters brain cells, that unchanged 14C-labelled AZQ does not penetrate the BBB as readily as expected, and that misonidazole easily exchanges across tumor and brain capillaries. Opening of the BBB and enhanced drug delivery to the brain would be achieved with intra-arterial infusions of hyperosmotic solutions but not with the inhalation of 20% CO2. In work with the metastatic Walker 256 brain tumor model, blood flow (BF) and glucose utilization (GU) were greatly reduced and blood-tissue transfer (BTT) was increased at foci within the large tumor masses; in tumor tissue around these foci, BF was low, GU was normal to higher than normal, and BTT was very high. For the small metastatic masses, GU was markedly increased, whereas BTT and BF were normal. For the oligodendroglioma model, BF, BTT, and GU were all normal or nearly normal for both large and small tumor masses.